Following is the procedure how to made a banner change.
What I did may not a good idea for made a banner
change under different category using the same module.

When you create the category there have an 'id' or
'storytopic' which you can use as checking parameter.
The disadvantage of this idea is when you add more topic
or category you have to modify the file to add more items
too. It's much better if it under database and auto related
to the topic id.

1. Create PHP file for check environment variable

if ($HTTP_GET_VARS['storytopic'] == 1) {
$xoopsTpl->assign('xoops_imageurl','logo1.jpg');
}

if ($HTTP_GET_VARS['storytopic'] == 2) {
$xoopsTpl->assign('xoops_imageurl','logo2.jpg');
}

2. Include the above file in the header.php

Then you can related variable $xoops_imageurl to
file 'theme.html' under themes folder.


Cheer